Friendly greetings denizens of the Firing Line. It is I, again, with yet another question.

When you're dealing with sights on a handgun, especially a model with changeable front sights and a bead (for instance classic three dot sight) how much of the accuracy is the sight and how much of it is the shooter? For instance I was firing a weapon today where the front post was too tall, resulting in a lot of off shots in terms of elevation. When the front sight was swapped for a shorter one the shots were still off, but in the opposite direction.

Is this a lesser of two evils situation? Is it better to knuckle down and learn to compensate and/or work with your weapon, or is this to be considered an issue with the weapon itself?